1. Field of the Invention
This invention relates to a washing process for delicate fabrics of wool or silk.
2. Description of Related Art
Detergents suitable for washing highly sensitive fabrics of wool or silk are known. Such known detergents generally show a neutral to mildly alkaline reaction and, in addition to anionic surfactants such as alkyl benzene sulfonate, fatty alcohol sulfate or alkyl glycol ether sulfate, often contain nonionic or cationic compounds. The nonionic surfactants are intended to increase detergency while the cationic compounds are intended to improve the softness and feel of the washed fabrics. However, it has been found that a number of anionic surfactants, such as alkyl benzene sulfonates for example, damage the fiber structure of sensitive, washable wools, particularly merino and angora, upon repeated use; whereas fatty alcohol sulfates, for example, do not wash satisfactorily at the low washing temperatures necessary. Nonionic surfactants have also proved to be unsatisfactory in such instances, because sensitive woolen fabrics washed with them feel comparatively hard and brittle. These effects can be considerably intensified with machine-washing. An addition of softening cationic surfactants, as recommended for purposes such as these, does not completely counteract the loss of feel and, where anionic surfactants are simultaneously present, leads to a reduction in detergency.
Additions of builder salts, such as pyrophosphates showing a mild alkaline reaction or free alkanolamine, have also been recommended for increasing detergency, but unfortunately their use likewise results in a loss of quality in the case of particularly sensitive woven or knitted woolen fabrics. Fatty acid mono- and diethanolamides are also known additives for light-duty detergents. However, their high foaming activity means that the wash liquor frequently overfoams when used in washing machines, particularly in automatic washing machines with a horizontally mounted drum. This applies in particular where foaming-active anionic surfactants are present.